Field of the Invention
Aspects of the present disclosure generally relate to an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus.
Description of the Related Art
In electrophotographic processes, recently, an increase in recording speed and an increase in image quality have been increasingly demanded. In order to respond to this, a further improvement in responsiveness and an improvement against causes for degrading image quality, such as a ghost phenomenon, are also desired for electrophotographic photosensitive members. Japanese Patent Application. Laid-Open No. 2008-74714 discusses a technique using a charge transporting material having a high charge mobility in the charge transport layer so as to increase the responsiveness of an electrophotographic photosensitive member.
Furthermore, in a case where the charge transport layer serves as a surface layer or uppermost layer, it is further required to be resistant to externally applied electrical and mechanical forces. Accordingly, Japanese Patent No. 4,246,621 and Japanese Patent Application Laid-Open No. 2006-53549 discuss techniques using a photosensitive member including a surface layer made of a polyester resin having a high mechanical strength. Japanese Patent No. 4,246,621 discusses an electrophotographic photosensitive member including a surface layer made of a polyester resin having a branched-chain structure. Japanese Patent Application Laid-Open No. 2006-53549 discusses an electrophotographic photosensitive member including a surface layer made of a polyester resin containing a diphenyl ether dicarboxylic acid moiety. Any of these discussions describes that the durability of the electrophotographic photosensitive member is improved.